Electrode structure for solid polymer type fuel cell

Abstract

A water holding layer having a carbon-based material and a water holding material is arranged on an anode diffusion layer. The water holding material is contained at 5 to 20 wt % of total weight of the water holding material and an electron conductive material. Alternatively, carbon particles having water absorption amount at saturated water vapor pressure at 60° C. is not less than 150 cc/g are contained in the anode diffusion layer. Water absorption ratio of the anode diffusion layer at 60° C. is in a range of 40 to 85%, a differential pressure is in a range of 60 to 120 mmaq, and a ratio of quantity of electric charge of catalytic material of the cathode catalytic layer existing in proton conductive passage from the polymer electrolyte membrane is not less than 15% of the quantity of electric charge of all the catalytic material existing in the cathode catalytic layer. Furthermore, a layer including carbon particles having water absorption amount at saturated water vapor pressure at 60° C. of not less than 150 cc/g and fluorine resin, is arranged on a carbon-based material having a contact angle with water of not more than 90° by performing a hydrophilic treatment. The water absorption ratio at 60° C. is in a range of 40 to 85 wt %, and the penetration resistance is not more than 5 mΩ.

1 . A membrane electrode assembly for a polymer electrolyte fuel cell, comprising: 
 a polymer electrolyte membrane; and    an anode and a cathode each having a catalytic layer and a diffusion layer,    the anode diffusion layer further comprising:    a carbon-based material; and    a water holding layer thereon containing water holding material for 5 to 20 wt % of total weight of an electron conductive material and the water holding material, or carbon particles having water absorption amount at saturated water vapor pressure at 60° C. of not less than 150 cc/g,    wherein water absorption ratio of the anode diffusion layer at 60° C. is in a range of 40 to 85%,    wherein a differential pressure measured by the differential pressure measuring method is in a range of 60 to 120 mmaq, and    wherein a ratio of quantity of electric charge of catalytic material of the cathode catalytic layer existing in proton conductive passage from the polymer electrolyte membrane measured by a cyclic voltammetric method is not less than 15% of the quantity of electric charge of all the catalytic material existing in the cathode catalytic layer.    
   
   
       2 . The membrane electrode assembly for a polymer electrolyte fuel cell according to  claim 1 , wherein the anode diffusion layer comprises: 
 a carbon-based material;    a layer thereon having carbon particles and fluorine resin; and    a layer thereon having carbon particles, a polymer electrolyte, void forming agent, and water holding material.    
   
   
       3 . The membrane electrode assembly for a polymer electrolyte fuel cell according to  claim 1 , wherein the anode diffusion layer comprises: 
 a carbon-based material;    a layer thereon having carbon particles, fluorine resin, and water holding material.    
   
   
       4 . A membrane electrode assembly for a polymer electrolyte fuel cell, comprising: 
 a polymer electrolyte membrane; and    an anode and a cathode each having a catalytic layer and a diffusion layer,    the anode diffusion layer further comprising:    a carbon-based material having a contact angle with water of not more than 90° by performing a hydrophilic treatment; and    a layer thereon having carbon particles having water absorption amount at saturated water vapor pressure at 60° C. of not less than 150 cc/g and fluorine resin,    wherein water absorption ratio of the anode diffusion layer at 60° C. is in a range of 40 to 85%,    wherein penetration resistance measured by a penetration resistance method is not more than 5 mΩ,    wherein a differential pressure measured by the differential pressure measuring method is in a range of 60 to 120 mmaq, and    wherein a ratio of quantity of electric charge of catalytic material of the cathode catalytic layer existing in proton conductive passage from the polymer electrolyte membrane measured by a cyclic voltammetric method is not less than 15% of the quantity of electric charge of all the catalytic material existing in the cathode catalytic layer.    
   
   
       5 . A membrane electrode assembly for a polymer electrolyte fuel cell, comprising: 
 a polymer electrolyte membrane; and    an anode and a cathode each having a catalytic layer and a diffusion layer,    the catalytic layer comprising:    at least a catalyst;    carbon particles supporting the catalyst; and    polymer electrolyte,    the cathode catalytic layer further contains void forming agent,    the diffusion layer comprising:    a carbon-based material; and    a layer thereon containing carbon particles and fluorine resin,    wherein water absorption amount at saturated water vapor pressure at 60° C. of the carbon particles of the anode diffusion layer is not less than 150 cc/g and water absorption amount at saturated water vapor pressure at 60° C. of the carbon particles of the cathode diffusion layer is less than 150 cc/g,    wherein water absorption ratio of the anode diffusion layer at 60° C. is in a range of 40 to 85%,    wherein a differential pressure of the anode diffusion layer and the cathode diffusion layer measured by the differential pressure measuring method is in a range of 60 to 120 mmaq and penetration resistance measured by a penetration resistance method is not more than 5 mΩ, and    wherein a ratio of quantity of electric charge of catalytic material of the cathode catalytic layer existing in proton conductive passage from the polymer electrolyte membrane measured by a cyclic voltammetric method is not less than 15% of the quantity of electric charge of all the catalytic material existing in the cathode catalytic layer.    
   
   
       6 . The membrane electrode assembly for a polymer electrolyte fuel cell according to  claim 5 , wherein the carbon-based material of the anode diffusion layer has contact angle with water of not more than 90° by performing a hydrophilic treatment, and the carbon-based material of the cathode diffusion layer has a contact angle with water of not less than 130° by performing a water-repellent treatment.